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<a href="app_8hpp.html">Go to the documentation of this file.</a><div class="fragment"><div class="line"><a id="l00001" name="l00001"></a><span class="lineno">    1</span><span class="comment">/* Flow-IPC: Sessions</span></div>
<div class="line"><a id="l00002" name="l00002"></a><span class="lineno">    2</span><span class="comment"> * Copyright 2023 Akamai Technologies, Inc.</span></div>
<div class="line"><a id="l00003" name="l00003"></a><span class="lineno">    3</span><span class="comment"> *</span></div>
<div class="line"><a id="l00004" name="l00004"></a><span class="lineno">    4</span><span class="comment"> * Licensed under the Apache License, Version 2.0 (the</span></div>
<div class="line"><a id="l00005" name="l00005"></a><span class="lineno">    5</span><span class="comment"> * &quot;License&quot;); you may not use this file except in</span></div>
<div class="line"><a id="l00006" name="l00006"></a><span class="lineno">    6</span><span class="comment"> * compliance with the License.  You may obtain a copy</span></div>
<div class="line"><a id="l00007" name="l00007"></a><span class="lineno">    7</span><span class="comment"> * of the License at</span></div>
<div class="line"><a id="l00008" name="l00008"></a><span class="lineno">    8</span><span class="comment"> *</span></div>
<div class="line"><a id="l00009" name="l00009"></a><span class="lineno">    9</span><span class="comment"> *   https://www.apache.org/licenses/LICENSE-2.0</span></div>
<div class="line"><a id="l00010" name="l00010"></a><span class="lineno">   10</span><span class="comment"> *</span></div>
<div class="line"><a id="l00011" name="l00011"></a><span class="lineno">   11</span><span class="comment"> * Unless required by applicable law or agreed to in</span></div>
<div class="line"><a id="l00012" name="l00012"></a><span class="lineno">   12</span><span class="comment"> * writing, software distributed under the License is</span></div>
<div class="line"><a id="l00013" name="l00013"></a><span class="lineno">   13</span><span class="comment"> * distributed on an &quot;AS IS&quot; BASIS, WITHOUT WARRANTIES OR</span></div>
<div class="line"><a id="l00014" name="l00014"></a><span class="lineno">   14</span><span class="comment"> * CONDITIONS OF ANY KIND, either express or implied.</span></div>
<div class="line"><a id="l00015" name="l00015"></a><span class="lineno">   15</span><span class="comment"> * See the License for the specific language governing</span></div>
<div class="line"><a id="l00016" name="l00016"></a><span class="lineno">   16</span><span class="comment"> * permissions and limitations under the License. */</span></div>
<div class="line"><a id="l00017" name="l00017"></a><span class="lineno">   17</span><span class="comment"></span> </div>
<div class="line"><a id="l00018" name="l00018"></a><span class="lineno">   18</span><span class="comment">/// @file</span></div>
<div class="line"><a id="l00019" name="l00019"></a><span class="lineno">   19</span><span class="comment"></span><span class="preprocessor">#pragma once</span></div>
<div class="line"><a id="l00020" name="l00020"></a><span class="lineno">   20</span> </div>
<div class="line"><a id="l00021" name="l00021"></a><span class="lineno">   21</span><span class="preprocessor">#include &quot;<a class="code" href="util__fwd_8hpp.html">ipc/util/util_fwd.hpp</a>&quot;</span></div>
<div class="line"><a id="l00022" name="l00022"></a><span class="lineno">   22</span><span class="preprocessor">#include &lt;boost/unordered_set.hpp&gt;</span></div>
<div class="line"><a id="l00023" name="l00023"></a><span class="lineno">   23</span> </div>
<div class="line"><a id="l00024" name="l00024"></a><span class="lineno">   24</span><span class="keyword">namespace </span><a class="code hl_namespace" href="namespaceipc_1_1session.html">ipc::session</a></div>
<div class="line"><a id="l00025" name="l00025"></a><span class="lineno">   25</span>{</div>
<div class="line"><a id="l00026" name="l00026"></a><span class="lineno">   26</span> </div>
<div class="line"><a id="l00027" name="l00027"></a><span class="lineno">   27</span><span class="comment">// Types.</span></div>
<div class="line"><a id="l00028" name="l00028"></a><span class="lineno">   28</span><span class="comment"></span> </div>
<div class="line"><a id="l00029" name="l00029"></a><span class="lineno">   29</span><span class="comment">/**</span></div>
<div class="line"><a id="l00030" name="l00030"></a><span class="lineno">   30</span><span class="comment"> * A *description* of an application in this ipc::session inter-process communication universe.  An application is,</span></div>
<div class="line"><a id="l00031" name="l00031"></a><span class="lineno">   31</span><span class="comment"> * at least roughly speaking, 1-1 with a distinct executable presumably interested in communicating with another such</span></div>
<div class="line"><a id="l00032" name="l00032"></a><span class="lineno">   32</span><span class="comment"> * executable.  A process is an instance of an application that has begun execution at some point.</span></div>
<div class="line"><a id="l00033" name="l00033"></a><span class="lineno">   33</span><span class="comment"> *</span></div>
<div class="line"><a id="l00034" name="l00034"></a><span class="lineno">   34</span><span class="comment"> * An App is a *description* of an application, and typically used (at least after program initialization, before</span></div>
<div class="line"><a id="l00035" name="l00035"></a><span class="lineno">   35</span><span class="comment"> * actual IPC begins) only as supertype of Client_app and/or Server_app, it is possible that 2+ `App`s exist but</span></div>
<div class="line"><a id="l00036" name="l00036"></a><span class="lineno">   36</span><span class="comment"> * describe one actual application but in different roles.  2+ such `App`s must have all members equal to each</span></div>
<div class="line"><a id="l00037" name="l00037"></a><span class="lineno">   37</span><span class="comment"> * other respectively.  In particular see App::m_name.</span></div>
<div class="line"><a id="l00038" name="l00038"></a><span class="lineno">   38</span><span class="comment"> *</span></div>
<div class="line"><a id="l00039" name="l00039"></a><span class="lineno">   39</span><span class="comment"> * This is a data store (and a simple one).  The same holds of Client_app and Server_app.  As of this writing</span></div>
<div class="line"><a id="l00040" name="l00040"></a><span class="lineno">   40</span><span class="comment"> * there are no rigid rules as to the existence of an App/Client_app/Server_app with this or that stored inside.</span></div>
<div class="line"><a id="l00041" name="l00041"></a><span class="lineno">   41</span><span class="comment"> * Make them all day long, if you want!  More restrictions shall come into play only when passing various</span></div>
<div class="line"><a id="l00042" name="l00042"></a><span class="lineno">   42</span><span class="comment"> * App objects and sub-objects (in some form) to ipc::session APIs, most notably the Session concept and buddies.</span></div>
<div class="line"><a id="l00043" name="l00043"></a><span class="lineno">   43</span><span class="comment"> *</span></div>
<div class="line"><a id="l00044" name="l00044"></a><span class="lineno">   44</span><span class="comment"> * However, to be useful, we suggest the following convention.  Some key ipc::session APIs may rely on it.</span></div>
<div class="line"><a id="l00045" name="l00045"></a><span class="lineno">   45</span><span class="comment"> *</span></div>
<div class="line"><a id="l00046" name="l00046"></a><span class="lineno">   46</span><span class="comment"> * ### App, Client_app, Server_app registry conventions ###</span></div>
<div class="line"><a id="l00047" name="l00047"></a><span class="lineno">   47</span><span class="comment"> * - Maintain a global (to the applications in your IPC universe) registry of known applications.  It could be</span></div>
<div class="line"><a id="l00048" name="l00048"></a><span class="lineno">   48</span><span class="comment"> *   stored in JSON or XML form in some central shared software component and read-into a master `set` or</span></div>
<div class="line"><a id="l00049" name="l00049"></a><span class="lineno">   49</span><span class="comment"> *   `unordered_set` (by App::m_name; see its doc header) available in a centrally-available library;</span></div>
<div class="line"><a id="l00050" name="l00050"></a><span class="lineno">   50</span><span class="comment"> *   or this `*set` could simply be a hard-coded C++ `extern const`; whatever works.</span></div>
<div class="line"><a id="l00051" name="l00051"></a><span class="lineno">   51</span><span class="comment"> * - In the current model supported by ipc::session: Suppose app Ap wants to communicate with app Bp; this is</span></div>
<div class="line"><a id="l00052" name="l00052"></a><span class="lineno">   52</span><span class="comment"> *   called the A-B *split*.  In any A-B split, one must be chosen as the *client*, the other as the *server*;</span></div>
<div class="line"><a id="l00053" name="l00053"></a><span class="lineno">   53</span><span class="comment"> *   let&#39;s by convention here assume they&#39;re always listed in server-client order.  However, it is allowed that</span></div>
<div class="line"><a id="l00054" name="l00054"></a><span class="lineno">   54</span><span class="comment"> *   two splits A-B and C-A co-exist in the same universe; meaning A is server when speaking to B but</span></div>
<div class="line"><a id="l00055" name="l00055"></a><span class="lineno">   55</span><span class="comment"> *   client when speaking to C.  Lastly, for each server app X, there is a global list of distinct client</span></div>
<div class="line"><a id="l00056" name="l00056"></a><span class="lineno">   56</span><span class="comment"> *   apps that are allowed to initiate IPC sessions with it (see ipc::Session concept).  Given that:</span></div>
<div class="line"><a id="l00057" name="l00057"></a><span class="lineno">   57</span><span class="comment"> *   - An App (in the above-described global registry) that is a client in any split shall be copied-into a</span></div>
<div class="line"><a id="l00058" name="l00058"></a><span class="lineno">   58</span><span class="comment"> *     (separate) Client_app object.</span></div>
<div class="line"><a id="l00059" name="l00059"></a><span class="lineno">   59</span><span class="comment"> *     - This global registry of known client applications shall similarly be maintained as a global `*set`.</span></div>
<div class="line"><a id="l00060" name="l00060"></a><span class="lineno">   60</span><span class="comment"> *       (The information regarding which apps are clients, too, can be read from JSON/XML/whatever or hard-coded.)</span></div>
<div class="line"><a id="l00061" name="l00061"></a><span class="lineno">   61</span><span class="comment"> *   - Similarly an App that is a server in any split shall be copied-into a (separate) Server_app object,</span></div>
<div class="line"><a id="l00062" name="l00062"></a><span class="lineno">   62</span><span class="comment"> *     forming the 3rd and final global `*set` of applications.</span></div>
<div class="line"><a id="l00063" name="l00063"></a><span class="lineno">   63</span><span class="comment"> *     - For each such Server_app, save the Client::m_name of each Client_app allowed to initiate sessions</span></div>
<div class="line"><a id="l00064" name="l00064"></a><span class="lineno">   64</span><span class="comment"> *       with it into its Server_app::m_allowed_client_apps.  (Again, this mapping can be read from JSON/XML/whatever</span></div>
<div class="line"><a id="l00065" name="l00065"></a><span class="lineno">   65</span><span class="comment"> *       or be hard-coded in some fashion.  In the end, though, it would go into `m_allowed_client_apps`.)</span></div>
<div class="line"><a id="l00066" name="l00066"></a><span class="lineno">   66</span><span class="comment"> *</span></div>
<div class="line"><a id="l00067" name="l00067"></a><span class="lineno">   67</span><span class="comment"> * Thus one would end up with, after initialization of each process wishing to participate in a given IPC universe:</span></div>
<div class="line"><a id="l00068" name="l00068"></a><span class="lineno">   68</span><span class="comment"> *   - An immutable `*set` of `App`s (global App registry).</span></div>
<div class="line"><a id="l00069" name="l00069"></a><span class="lineno">   69</span><span class="comment"> *   - An immutable `*set` of `Client_app`s (global Client_app registry).</span></div>
<div class="line"><a id="l00070" name="l00070"></a><span class="lineno">   70</span><span class="comment"> *   - An immutable `*set` of `Server_app`s (global Server_app registry), each Server_app listing the `m_name`s</span></div>
<div class="line"><a id="l00071" name="l00071"></a><span class="lineno">   71</span><span class="comment"> *     of `Client_app`s referring to the applications that may initiate sessions with it in its immutable</span></div>
<div class="line"><a id="l00072" name="l00072"></a><span class="lineno">   72</span><span class="comment"> *     Server_app::m_allowed_client_apps.</span></div>
<div class="line"><a id="l00073" name="l00073"></a><span class="lineno">   73</span><span class="comment"> *</span></div>
<div class="line"><a id="l00074" name="l00074"></a><span class="lineno">   74</span><span class="comment"> * There should be no need, from this moment on, to copy any App, Client_app, or Server_app.  It shall be passed</span></div>
<div class="line"><a id="l00075" name="l00075"></a><span class="lineno">   75</span><span class="comment"> * by `const` reference.</span></div>
<div class="line"><a id="l00076" name="l00076"></a><span class="lineno">   76</span><span class="comment"> */</span></div>
<div class="line"><a id="l00077" name="l00077"></a><span class="lineno"><a class="line" href="structipc_1_1session_1_1App.html">   77</a></span><span class="keyword">struct </span><a class="code hl_struct" href="structipc_1_1session_1_1App.html">App</a></div>
<div class="line"><a id="l00078" name="l00078"></a><span class="lineno">   78</span>{</div>
<div class="line"><a id="l00079" name="l00079"></a><span class="lineno">   79</span>  <span class="comment">// Types.</span></div>
<div class="line"><a id="l00080" name="l00080"></a><span class="lineno">   80</span><span class="comment"></span> </div>
<div class="line"><a id="l00081" name="l00081"></a><span class="lineno">   81</span><span class="comment">  /// Suggested type for storing master repository or all `Apps`s.  See App doc header for discussion.</span></div>
<div class="line"><a id="l00082" name="l00082"></a><span class="lineno"><a class="line" href="structipc_1_1session_1_1App.html#af7527bc1ad0cde62cd4fde97bc1d7ecc">   82</a></span><span class="comment"></span>  <span class="keyword">using </span><a class="code hl_typedef" href="structipc_1_1session_1_1App.html#af7527bc1ad0cde62cd4fde97bc1d7ecc">Master_set</a> = boost::unordered_map&lt;std::string, App&gt;;</div>
<div class="line"><a id="l00083" name="l00083"></a><span class="lineno">   83</span> </div>
<div class="line"><a id="l00084" name="l00084"></a><span class="lineno">   84</span>  <span class="comment">// Data.</span></div>
<div class="line"><a id="l00085" name="l00085"></a><span class="lineno">   85</span><span class="comment"></span> </div>
<div class="line"><a id="l00086" name="l00086"></a><span class="lineno">   86</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00087" name="l00087"></a><span class="lineno">   87</span><span class="comment">   * Brief application name, readable to humans and unique across all other applications&#39; names; used</span></div>
<div class="line"><a id="l00088" name="l00088"></a><span class="lineno">   88</span><span class="comment">   * both as a short programmatic key in shared resource naming (including as a folder in #Shared_name for</span></div>
<div class="line"><a id="l00089" name="l00089"></a><span class="lineno">   89</span><span class="comment">   * kernel-persistent resources and addresses; and in path names -- such as PID file name -- in the file system).</span></div>
<div class="line"><a id="l00090" name="l00090"></a><span class="lineno">   90</span><span class="comment">   *</span></div>
<div class="line"><a id="l00091" name="l00091"></a><span class="lineno">   91</span><span class="comment">   * ### Convention: mandated use as key ###</span></div>
<div class="line"><a id="l00092" name="l00092"></a><span class="lineno">   92</span><span class="comment">   * Neither App nor any nearby sub-class or alias of App (Client_app, Server_app) shall be used as the key type</span></div>
<div class="line"><a id="l00093" name="l00093"></a><span class="lineno">   93</span><span class="comment">   * in an associative container (e.g., `set`, `unordered_map`).  Instead App::m_name shall be used as the key</span></div>
<div class="line"><a id="l00094" name="l00094"></a><span class="lineno">   94</span><span class="comment">   * when lookup by distinct application is desired.  Two scenarios come to mind:</span></div>
<div class="line"><a id="l00095" name="l00095"></a><span class="lineno">   95</span><span class="comment">   *   - You want to store a set of applications fitting some criterion/a, but this is not some master repository</span></div>
<div class="line"><a id="l00096" name="l00096"></a><span class="lineno">   96</span><span class="comment">   *     of App objects in the first place -- rather it is referring to some subset of such a master repository.</span></div>
<div class="line"><a id="l00097" name="l00097"></a><span class="lineno">   97</span><span class="comment">   *     - Then, store simply a `set` or `unordered_set` (etc.) of `std::string m_name`s.</span></div>
<div class="line"><a id="l00098" name="l00098"></a><span class="lineno">   98</span><span class="comment">   *       - Rationale: The basic desired operation here is an exitence-check (is application X present, based on</span></div>
<div class="line"><a id="l00099" name="l00099"></a><span class="lineno">   99</span><span class="comment">   *         some definition of present?).  #m_name is by definition guaranteed to be distinct from all others.</span></div>
<div class="line"><a id="l00100" name="l00100"></a><span class="lineno">  100</span><span class="comment">   *         Hence storing such strings alone is sufficient and reasonably efficient while also not relying on</span></div>
<div class="line"><a id="l00101" name="l00101"></a><span class="lineno">  101</span><span class="comment">   *         App address uniqueness for lookup (which, while efficient, is a pain to maintain).</span></div>
<div class="line"><a id="l00102" name="l00102"></a><span class="lineno">  102</span><span class="comment">   *   - You want to store some master repository of App objects, with all their config such as UID, GID, etc.</span></div>
<div class="line"><a id="l00103" name="l00103"></a><span class="lineno">  103</span><span class="comment">   *     - Then, store a `map` or `unordered_map`, with the keys being `std::string m_name`s,</span></div>
<div class="line"><a id="l00104" name="l00104"></a><span class="lineno">  104</span><span class="comment">   *       while the values are filled-out App objects (or objects of App sub-class) -- with the guarantee</span></div>
<div class="line"><a id="l00105" name="l00105"></a><span class="lineno">  105</span><span class="comment">   *       that `M[name].m_name == name` for all `name`s in any such `M`.</span></div>
<div class="line"><a id="l00106" name="l00106"></a><span class="lineno">  106</span><span class="comment">   *       - Rationale: Same as above; but in addition to being able to perform existence-check by #m_name,</span></div>
<div class="line"><a id="l00107" name="l00107"></a><span class="lineno">  107</span><span class="comment">   *         one can also iterate through the master details of all the applications and/or</span></div>
<div class="line"><a id="l00108" name="l00108"></a><span class="lineno">  108</span><span class="comment">   *         lookup a given application&#39;s master details.</span></div>
<div class="line"><a id="l00109" name="l00109"></a><span class="lineno">  109</span><span class="comment">   *</span></div>
<div class="line"><a id="l00110" name="l00110"></a><span class="lineno">  110</span><span class="comment">   * Due to these conventions:</span></div>
<div class="line"><a id="l00111" name="l00111"></a><span class="lineno">  111</span><span class="comment">   *   - We do not supply the usual complement of associative-container &quot;stuff&quot; for App and buddies:</span></div>
<div class="line"><a id="l00112" name="l00112"></a><span class="lineno">  112</span><span class="comment">   *     equality, less-than, hashing.  We do not want to encourage direct App storage that way.</span></div>
<div class="line"><a id="l00113" name="l00113"></a><span class="lineno">  113</span><span class="comment">   *   - The idea is: When such storage is desired, use that usual complement of associative-container &quot;stuff&quot;</span></div>
<div class="line"><a id="l00114" name="l00114"></a><span class="lineno">  114</span><span class="comment">   *     that is already supplied for `std::string`, as applied to App::m_name.</span></div>
<div class="line"><a id="l00115" name="l00115"></a><span class="lineno">  115</span><span class="comment">   *</span></div>
<div class="line"><a id="l00116" name="l00116"></a><span class="lineno">  116</span><span class="comment">   * Digression regarding rationale: Why use #m_name, and not (say) `const App*`, as the key in associative</span></div>
<div class="line"><a id="l00117" name="l00117"></a><span class="lineno">  117</span><span class="comment">   * lookups?  Answer: It was considered.  Due to the infrequency of such lookups, combined with the</span></div>
<div class="line"><a id="l00118" name="l00118"></a><span class="lineno">  118</span><span class="comment">   * debug-friendliness/expressiveness of referring to a distinct app by its user-readable name, the lookup-by-name</span></div>
<div class="line"><a id="l00119" name="l00119"></a><span class="lineno">  119</span><span class="comment">   * convention felt more straightforward and convenient.  Plus, the address of an object stored in a container</span></div>
<div class="line"><a id="l00120" name="l00120"></a><span class="lineno">  120</span><span class="comment">   * may change while it is being built, which would add an element of brittleness.  One could also use an</span></div>
<div class="line"><a id="l00121" name="l00121"></a><span class="lineno">  121</span><span class="comment">   * iterator as a key, but then the registry container would be mandated to be iteratator-stable-under-insertion,</span></div>
<div class="line"><a id="l00122" name="l00122"></a><span class="lineno">  122</span><span class="comment">   * and that brings an annoying host of worries.  Indexing by string name is solid by comparison, if a bit slower.</span></div>
<div class="line"><a id="l00123" name="l00123"></a><span class="lineno">  123</span><span class="comment">   *</span></div>
<div class="line"><a id="l00124" name="l00124"></a><span class="lineno">  124</span><span class="comment">   * ### Conventions: Naming ###</span></div>
<div class="line"><a id="l00125" name="l00125"></a><span class="lineno">  125</span><span class="comment">   * Must begin with an ASCII alphabetical character and otherwise consist of only ASCII alphanumerics and underscores.</span></div>
<div class="line"><a id="l00126" name="l00126"></a><span class="lineno">  126</span><span class="comment">   * While these are partially conventions driven by style (for example, dashes could also be allowed -- we just</span></div>
<div class="line"><a id="l00127" name="l00127"></a><span class="lineno">  127</span><span class="comment">   * do not want them to be, so that underscores are always the word-separator used consistently), the following</span></div>
<div class="line"><a id="l00128" name="l00128"></a><span class="lineno">  128</span><span class="comment">   * is an important guarantee for related #Shared_name and `fs::path` semantics:</span></div>
<div class="line"><a id="l00129" name="l00129"></a><span class="lineno">  129</span><span class="comment">   *   - Must not contain a util::Shared_name::S_SEPARATOR.</span></div>
<div class="line"><a id="l00130" name="l00130"></a><span class="lineno">  130</span><span class="comment">   *   - Must not contain a forward-slash or any other file system path separator.</span></div>
<div class="line"><a id="l00131" name="l00131"></a><span class="lineno">  131</span><span class="comment">   *   - Must not contain a dot or any other conceivable extension separator (other than underscore).</span></div>
<div class="line"><a id="l00132" name="l00132"></a><span class="lineno">  132</span><span class="comment">   *</span></div>
<div class="line"><a id="l00133" name="l00133"></a><span class="lineno">  133</span><span class="comment">   * Therefore:</span></div>
<div class="line"><a id="l00134" name="l00134"></a><span class="lineno">  134</span><span class="comment">   *   - In #Shared_name paths one can embed #m_name by preceding and/or succeeding it with a</span></div>
<div class="line"><a id="l00135" name="l00135"></a><span class="lineno">  135</span><span class="comment">   *     util::Shared_name::S_SEPARATOR, thus making it a full or partial folder name.</span></div>
<div class="line"><a id="l00136" name="l00136"></a><span class="lineno">  136</span><span class="comment">   *   - In file system paths one can embed #m_name by preceding and/or succeeding it with a</span></div>
<div class="line"><a id="l00137" name="l00137"></a><span class="lineno">  137</span><span class="comment">   *     forward-slash, thus making it a full or partial directory name.</span></div>
<div class="line"><a id="l00138" name="l00138"></a><span class="lineno">  138</span><span class="comment">   *   - In either: one can embed #m_name by preceding and/or succeeding it with a dot as an extension separator.</span></div>
<div class="line"><a id="l00139" name="l00139"></a><span class="lineno">  139</span><span class="comment">   *</span></div>
<div class="line"><a id="l00140" name="l00140"></a><span class="lineno">  140</span><span class="comment">   * So if #m_name is &quot;abc_def&quot; one can do things like &quot;/some/dir/abc_def/some_file&quot; and &quot;/some/dir/abc_def.pid/file&quot;</span></div>
<div class="line"><a id="l00141" name="l00141"></a><span class="lineno">  141</span><span class="comment">   * and &quot;/some/dir/prefix.abc_def.3&quot;.  I.e., #m_name can be safely used as a conceptual &quot;token,&quot; even when</span></div>
<div class="line"><a id="l00142" name="l00142"></a><span class="lineno">  142</span><span class="comment">   * combined with path/name separators and dot-extension naming.</span></div>
<div class="line"><a id="l00143" name="l00143"></a><span class="lineno">  143</span><span class="comment">   */</span></div>
<div class="line"><a id="l00144" name="l00144"></a><span class="lineno"><a class="line" href="structipc_1_1session_1_1App.html#a8e67b57829fe43a122a23c699b5de8fd">  144</a></span>  std::string <a class="code hl_variable" href="structipc_1_1session_1_1App.html#a8e67b57829fe43a122a23c699b5de8fd">m_name</a>;</div>
<div class="line"><a id="l00145" name="l00145"></a><span class="lineno">  145</span><span class="comment"></span> </div>
<div class="line"><a id="l00146" name="l00146"></a><span class="lineno">  146</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00147" name="l00147"></a><span class="lineno">  147</span><span class="comment">   * Absolute, lexically normalized canonical path to the executable entity (which is not a directory), as it</span></div>
<div class="line"><a id="l00148" name="l00148"></a><span class="lineno">  148</span><span class="comment">   * would appear in a command line or `exec()`-like invocation when actually invoking the application.</span></div>
<div class="line"><a id="l00149" name="l00149"></a><span class="lineno">  149</span><span class="comment">   * Formally (refer to cppreference.com `filesystem::path` doc page):</span></div>
<div class="line"><a id="l00150" name="l00150"></a><span class="lineno">  150</span><span class="comment">   *   - There is no root-name: No Windows drive letters (&quot;C:&quot;), no network file share (&quot;//share_name&quot;), etc.</span></div>
<div class="line"><a id="l00151" name="l00151"></a><span class="lineno">  151</span><span class="comment">   *   - It is a Unix path: Only forward-slash is used as separator, and that character always is a separator.</span></div>
<div class="line"><a id="l00152" name="l00152"></a><span class="lineno">  152</span><span class="comment">   *   - It is absolute: It starts with forward-slash.</span></div>
<div class="line"><a id="l00153" name="l00153"></a><span class="lineno">  153</span><span class="comment">   *   - It is lexically normalized: See reference, but essentially it means no more than one slash in a row,</span></div>
<div class="line"><a id="l00154" name="l00154"></a><span class="lineno">  154</span><span class="comment">   *     no dot components, no dot-dot components.  (Note: dots and dot-dots can *appear* -- but an *entire*</span></div>
<div class="line"><a id="l00155" name="l00155"></a><span class="lineno">  155</span><span class="comment">   *     component cannot comprise solely such a sequence; where component means: a thing preceded by slash and</span></div>
<div class="line"><a id="l00156" name="l00156"></a><span class="lineno">  156</span><span class="comment">   *     succeeded by slash or end-of-path.)</span></div>
<div class="line"><a id="l00157" name="l00157"></a><span class="lineno">  157</span><span class="comment">   *</span></div>
<div class="line"><a id="l00158" name="l00158"></a><span class="lineno">  158</span><span class="comment">   * Do note that because of the &quot;as it would appear in a command line...&quot; requirement this indirectly restricts</span></div>
<div class="line"><a id="l00159" name="l00159"></a><span class="lineno">  159</span><span class="comment">   * how processes are to be invoked in this system: always via 1, absolute, lexically normal path to the executable.</span></div>
<div class="line"><a id="l00160" name="l00160"></a><span class="lineno">  160</span><span class="comment">   * (Do also note this is still not necessary force an unambiguous way to invoke an application installed at</span></div>
<div class="line"><a id="l00161" name="l00161"></a><span class="lineno">  161</span><span class="comment">   * a given location: sym-links, at least, introduce an infinite number of ways to refer to the same binary.</span></div>
<div class="line"><a id="l00162" name="l00162"></a><span class="lineno">  162</span><span class="comment">   * That said, at least lexical normalization can be done programmatically in `fs`, and sym-link following</span></div>
<div class="line"><a id="l00163" name="l00163"></a><span class="lineno">  163</span><span class="comment">   * path resolution is also separately supplied by `fs`.)</span></div>
<div class="line"><a id="l00164" name="l00164"></a><span class="lineno">  164</span><span class="comment">   */</span></div>
<div class="line"><a id="l00165" name="l00165"></a><span class="lineno"><a class="line" href="structipc_1_1session_1_1App.html#ae82a8635858664720c8546e468f8090b">  165</a></span>  fs::path <a class="code hl_variable" href="structipc_1_1session_1_1App.html#ae82a8635858664720c8546e468f8090b">m_exec_path</a>;</div>
<div class="line"><a id="l00166" name="l00166"></a><span class="lineno">  166</span><span class="comment"></span> </div>
<div class="line"><a id="l00167" name="l00167"></a><span class="lineno">  167</span><span class="comment">  /// The application must run as this user ID (UID).  Files and other shared resources shall have this owner.</span></div>
<div class="line"><a id="l00168" name="l00168"></a><span class="lineno"><a class="line" href="structipc_1_1session_1_1App.html#a9e32297579603f2d96616976474d0246">  168</a></span><span class="comment"></span>  <a class="code hl_typedef" href="namespaceipc_1_1util.html#a6435c1b48ec8684c24ca406d1d17208e">util::user_id_t</a> <a class="code hl_variable" href="structipc_1_1session_1_1App.html#a9e32297579603f2d96616976474d0246">m_user_id</a>;</div>
<div class="line"><a id="l00169" name="l00169"></a><span class="lineno">  169</span><span class="comment"></span> </div>
<div class="line"><a id="l00170" name="l00170"></a><span class="lineno">  170</span><span class="comment">  /// The application must run as this group ID (GID).  Files and other shared resources shall have this owner.</span></div>
<div class="line"><a id="l00171" name="l00171"></a><span class="lineno"><a class="line" href="structipc_1_1session_1_1App.html#a78bb1e984835f429fd44869a83f4b093">  171</a></span><span class="comment"></span>  <a class="code hl_typedef" href="namespaceipc_1_1util.html#a3f7d069ce0d23f73153da2e2559dc3d3">util::group_id_t</a> <a class="code hl_variable" href="structipc_1_1session_1_1App.html#a78bb1e984835f429fd44869a83f4b093">m_group_id</a>;</div>
<div class="line"><a id="l00172" name="l00172"></a><span class="lineno">  172</span>}; <span class="comment">// struct App</span></div>
<div class="line"><a id="l00173" name="l00173"></a><span class="lineno">  173</span><span class="comment"></span> </div>
<div class="line"><a id="l00174" name="l00174"></a><span class="lineno">  174</span><span class="comment">/**</span></div>
<div class="line"><a id="l00175" name="l00175"></a><span class="lineno">  175</span><span class="comment"> * An App that is used as a client in at least one client-server IPC split.  This is explained in the</span></div>
<div class="line"><a id="l00176" name="l00176"></a><span class="lineno">  176</span><span class="comment"> * &quot;App, Client_app, Server_app registry conventions&quot; section of the `struct` App doc header.</span></div>
<div class="line"><a id="l00177" name="l00177"></a><span class="lineno">  177</span><span class="comment"> *</span></div>
<div class="line"><a id="l00178" name="l00178"></a><span class="lineno">  178</span><span class="comment"> * @see `struct` App doc header.</span></div>
<div class="line"><a id="l00179" name="l00179"></a><span class="lineno">  179</span><span class="comment"> *</span></div>
<div class="line"><a id="l00180" name="l00180"></a><span class="lineno">  180</span><span class="comment"> * As of this writing a Client_app is just an App with no added stored information.  That said a Server_app</span></div>
<div class="line"><a id="l00181" name="l00181"></a><span class="lineno">  181</span><span class="comment"> * may exist whose App base object is equals to a Client_app `*this`&#39;s App base object (in particular App::m_name</span></div>
<div class="line"><a id="l00182" name="l00182"></a><span class="lineno">  182</span><span class="comment"> * but also all other members).</span></div>
<div class="line"><a id="l00183" name="l00183"></a><span class="lineno">  183</span><span class="comment"> */</span></div>
<div class="line"><a id="l00184" name="l00184"></a><span class="lineno"><a class="line" href="structipc_1_1session_1_1Client__app.html">  184</a></span><span class="keyword">struct </span><a class="code hl_struct" href="structipc_1_1session_1_1Client__app.html">Client_app</a> : <span class="keyword">public</span> <a class="code hl_struct" href="structipc_1_1session_1_1App.html">App</a></div>
<div class="line"><a id="l00185" name="l00185"></a><span class="lineno">  185</span>{</div>
<div class="line"><a id="l00186" name="l00186"></a><span class="lineno">  186</span>  <span class="comment">// Types.</span></div>
<div class="line"><a id="l00187" name="l00187"></a><span class="lineno">  187</span><span class="comment"></span> </div>
<div class="line"><a id="l00188" name="l00188"></a><span class="lineno">  188</span><span class="comment">  /// Short-hand for base type.</span></div>
<div class="line"><a id="l00189" name="l00189"></a><span class="lineno"><a class="line" href="structipc_1_1session_1_1Client__app.html#a9d1ec69e821e034305e20cfbf1161a04">  189</a></span><span class="comment"></span>  <span class="keyword">using </span><a class="code hl_struct" href="structipc_1_1session_1_1App.html">Base</a> = <a class="code hl_struct" href="structipc_1_1session_1_1App.html">App</a>;</div>
<div class="line"><a id="l00190" name="l00190"></a><span class="lineno">  190</span><span class="comment"></span> </div>
<div class="line"><a id="l00191" name="l00191"></a><span class="lineno">  191</span><span class="comment">  /// Suggested type for storing master repository or all `Client_apps`s.  See App doc header for discussion.</span></div>
<div class="line"><a id="l00192" name="l00192"></a><span class="lineno"><a class="line" href="structipc_1_1session_1_1Client__app.html#add718cbf6aa1d2abb26fbadcc974a7bd">  192</a></span><span class="comment"></span>  <span class="keyword">using </span><a class="code hl_typedef" href="structipc_1_1session_1_1App.html#af7527bc1ad0cde62cd4fde97bc1d7ecc">Master_set</a> = boost::unordered_map&lt;std::string, Client_app&gt;;</div>
<div class="line"><a id="l00193" name="l00193"></a><span class="lineno">  193</span>};</div>
<div class="line"><a id="l00194" name="l00194"></a><span class="lineno">  194</span><span class="comment"></span> </div>
<div class="line"><a id="l00195" name="l00195"></a><span class="lineno">  195</span><span class="comment">/**</span></div>
<div class="line"><a id="l00196" name="l00196"></a><span class="lineno">  196</span><span class="comment"> * An App that is used as a server in at least one client-server IPC split.  This is explained in the</span></div>
<div class="line"><a id="l00197" name="l00197"></a><span class="lineno">  197</span><span class="comment"> * &quot;App, Client_app, Server_app registry conventions&quot; section of the `struct` App doc header.</span></div>
<div class="line"><a id="l00198" name="l00198"></a><span class="lineno">  198</span><span class="comment"> *</span></div>
<div class="line"><a id="l00199" name="l00199"></a><span class="lineno">  199</span><span class="comment"> * @see `struct` App doc header.</span></div>
<div class="line"><a id="l00200" name="l00200"></a><span class="lineno">  200</span><span class="comment"> *</span></div>
<div class="line"><a id="l00201" name="l00201"></a><span class="lineno">  201</span><span class="comment"> * As explained there, each Server_app -- in addition to the source App fields copied from an App in the master</span></div>
<div class="line"><a id="l00202" name="l00202"></a><span class="lineno">  202</span><span class="comment"> * App repository -- ultimately stores references (by App::m_name) to the `Client_app`s describing client apps</span></div>
<div class="line"><a id="l00203" name="l00203"></a><span class="lineno">  203</span><span class="comment"> * that may initiate sessions with that Server_app.</span></div>
<div class="line"><a id="l00204" name="l00204"></a><span class="lineno">  204</span><span class="comment"> */</span></div>
<div class="line"><a id="l00205" name="l00205"></a><span class="lineno"><a class="line" href="structipc_1_1session_1_1Server__app.html">  205</a></span><span class="keyword">struct </span><a class="code hl_struct" href="structipc_1_1session_1_1Server__app.html">Server_app</a> : <span class="keyword">public</span> <a class="code hl_struct" href="structipc_1_1session_1_1App.html">App</a></div>
<div class="line"><a id="l00206" name="l00206"></a><span class="lineno">  206</span>{</div>
<div class="line"><a id="l00207" name="l00207"></a><span class="lineno">  207</span>  <span class="comment">// Types.</span></div>
<div class="line"><a id="l00208" name="l00208"></a><span class="lineno">  208</span><span class="comment"></span> </div>
<div class="line"><a id="l00209" name="l00209"></a><span class="lineno">  209</span><span class="comment">  /// Suggested type for storing master repository or all `Server_apps`s.  See App doc header for discussion.</span></div>
<div class="line"><a id="l00210" name="l00210"></a><span class="lineno"><a class="line" href="structipc_1_1session_1_1Server__app.html#a1fc9e403e3b5c89a4cd328da829590a4">  210</a></span><span class="comment"></span>  <span class="keyword">using </span><a class="code hl_typedef" href="structipc_1_1session_1_1App.html#af7527bc1ad0cde62cd4fde97bc1d7ecc">Master_set</a> = boost::unordered_map&lt;std::string, Server_app&gt;;</div>
<div class="line"><a id="l00211" name="l00211"></a><span class="lineno">  211</span><span class="comment"></span> </div>
<div class="line"><a id="l00212" name="l00212"></a><span class="lineno">  212</span><span class="comment">  /// Short-hand for existence-checkable set of `Client_app`s via App::m_name.</span></div>
<div class="line"><a id="l00213" name="l00213"></a><span class="lineno"><a class="line" href="structipc_1_1session_1_1Server__app.html#a268ca127637100ab10a4ac296aff4fad">  213</a></span><span class="comment"></span>  <span class="keyword">using </span><a class="code hl_typedef" href="structipc_1_1session_1_1Server__app.html#a268ca127637100ab10a4ac296aff4fad">Client_app_set</a> = boost::unordered_set&lt;std::string&gt;;</div>
<div class="line"><a id="l00214" name="l00214"></a><span class="lineno">  214</span> </div>
<div class="line"><a id="l00215" name="l00215"></a><span class="lineno">  215</span>  <span class="comment">// Data.</span></div>
<div class="line"><a id="l00216" name="l00216"></a><span class="lineno">  216</span><span class="comment"></span> </div>
<div class="line"><a id="l00217" name="l00217"></a><span class="lineno">  217</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00218" name="l00218"></a><span class="lineno">  218</span><span class="comment">   * A given Client_app (as identified by its distinct App::m_name) may request to establish an IPC session</span></div>
<div class="line"><a id="l00219" name="l00219"></a><span class="lineno">  219</span><span class="comment">   * with an instance of `*this` Server_app as the conversation partner process if and only if</span></div>
<div class="line"><a id="l00220" name="l00220"></a><span class="lineno">  220</span><span class="comment">   * it is in this set.</span></div>
<div class="line"><a id="l00221" name="l00221"></a><span class="lineno">  221</span><span class="comment">   */</span></div>
<div class="line"><a id="l00222" name="l00222"></a><span class="lineno"><a class="line" href="structipc_1_1session_1_1Server__app.html#a12df649b33893270afeac7240a571633">  222</a></span>  <a class="code hl_typedef" href="structipc_1_1session_1_1Server__app.html#a268ca127637100ab10a4ac296aff4fad">Client_app_set</a> <a class="code hl_variable" href="structipc_1_1session_1_1Server__app.html#a12df649b33893270afeac7240a571633">m_allowed_client_apps</a>;</div>
<div class="line"><a id="l00223" name="l00223"></a><span class="lineno">  223</span><span class="comment"></span> </div>
<div class="line"><a id="l00224" name="l00224"></a><span class="lineno">  224</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00225" name="l00225"></a><span class="lineno">  225</span><span class="comment">   * Absolute path to the directory (without trailing separator) in the file system where kernel-persistent</span></div>
<div class="line"><a id="l00226" name="l00226"></a><span class="lineno">  226</span><span class="comment">   * runtime, but not temporary, information shall be placed for this particular application; leave empty to</span></div>
<div class="line"><a id="l00227" name="l00227"></a><span class="lineno">  227</span><span class="comment">   * use the default system path instead.  Informally: In production it is recommended to leave this</span></div>
<div class="line"><a id="l00228" name="l00228"></a><span class="lineno">  228</span><span class="comment">   * empty, as the default system path is a well known location (namely /var/run) where one would expect to find</span></div>
<div class="line"><a id="l00229" name="l00229"></a><span class="lineno">  229</span><span class="comment">   * such files.</span></div>
<div class="line"><a id="l00230" name="l00230"></a><span class="lineno">  230</span><span class="comment">   *</span></div>
<div class="line"><a id="l00231" name="l00231"></a><span class="lineno">  231</span><span class="comment">   * Kernel-persistent means that it&#39;ll disappear at reboot; runtime, but not temporary, means it&#39;s... not a</span></div>
<div class="line"><a id="l00232" name="l00232"></a><span class="lineno">  232</span><span class="comment">   * thing that might be wiped spuriously anytime (informally: not /tmp).  Informally: just know that it is normally</span></div>
<div class="line"><a id="l00233" name="l00233"></a><span class="lineno">  233</span><span class="comment">   * /var/run, and that it stores things such as process-ID (PID) files.</span></div>
<div class="line"><a id="l00234" name="l00234"></a><span class="lineno">  234</span><span class="comment">   *</span></div>
<div class="line"><a id="l00235" name="l00235"></a><span class="lineno">  235</span><span class="comment">   * It shall be a Unix path and absolute (starts with forward-slash) (and lacks a root-name).  Informally it is</span></div>
<div class="line"><a id="l00236" name="l00236"></a><span class="lineno">  236</span><span class="comment">   * probably best for it to be lexically normal as well.</span></div>
<div class="line"><a id="l00237" name="l00237"></a><span class="lineno">  237</span><span class="comment">   *</span></div>
<div class="line"><a id="l00238" name="l00238"></a><span class="lineno">  238</span><span class="comment">   * ### Rationale ###</span></div>
<div class="line"><a id="l00239" name="l00239"></a><span class="lineno">  239</span><span class="comment">   * Why allow this override, if the default is sensible?  Answer: The default usually requires admin privileges</span></div>
<div class="line"><a id="l00240" name="l00240"></a><span class="lineno">  240</span><span class="comment">   * for writing.  For test/debug purposes a location like /tmp or /tmp/var/run can be convenient.</span></div>
<div class="line"><a id="l00241" name="l00241"></a><span class="lineno">  241</span><span class="comment">   */</span></div>
<div class="line"><a id="l00242" name="l00242"></a><span class="lineno"><a class="line" href="structipc_1_1session_1_1Server__app.html#a4fa3317f8c57042789940be94f872500">  242</a></span>  fs::path <a class="code hl_variable" href="structipc_1_1session_1_1Server__app.html#a4fa3317f8c57042789940be94f872500">m_kernel_persistent_run_dir_override</a>;</div>
<div class="line"><a id="l00243" name="l00243"></a><span class="lineno">  243</span><span class="comment"></span> </div>
<div class="line"><a id="l00244" name="l00244"></a><span class="lineno">  244</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00245" name="l00245"></a><span class="lineno">  245</span><span class="comment">   * Specifies level of access for `Client_app`s (which must, also, be in #m_allowed_client_apps at any rate)</span></div>
<div class="line"><a id="l00246" name="l00246"></a><span class="lineno">  246</span><span class="comment">   * as enforced by file system permissions.</span></div>
<div class="line"><a id="l00247" name="l00247"></a><span class="lineno">  247</span><span class="comment">   *</span></div>
<div class="line"><a id="l00248" name="l00248"></a><span class="lineno">  248</span><span class="comment">   * Specifically, as of this writing, it determines at least the following items.  Note that ownership is</span></div>
<div class="line"><a id="l00249" name="l00249"></a><span class="lineno">  249</span><span class="comment">   * identified by the UID/GID settings (matching `*this` App::m_user_id and App::m_group_id) of various</span></div>
<div class="line"><a id="l00250" name="l00250"></a><span class="lineno">  250</span><span class="comment">   * files and other shared resources created by the server* application in the ipc::session framework.</span></div>
<div class="line"><a id="l00251" name="l00251"></a><span class="lineno">  251</span><span class="comment">   * (* - Actually, at times, resources are created by the client application too.  See below.)</span></div>
<div class="line"><a id="l00252" name="l00252"></a><span class="lineno">  252</span><span class="comment">   *   - File permissions set on the CNS (PID) file established by Session_server.  A given #Client_session</span></div>
<div class="line"><a id="l00253" name="l00253"></a><span class="lineno">  253</span><span class="comment">   *     (etc.) must read this file in order to know to which Session_server to issue a session-open request</span></div>
<div class="line"><a id="l00254" name="l00254"></a><span class="lineno">  254</span><span class="comment">   *     (establish a Session); if it cannot access that file, it cannot open a session against this</span></div>
<div class="line"><a id="l00255" name="l00255"></a><span class="lineno">  255</span><span class="comment">   *     Server_app.</span></div>
<div class="line"><a id="l00256" name="l00256"></a><span class="lineno">  256</span><span class="comment">   *     - If this check fails, and everything is functioning as generally intended internally, then the below</span></div>
<div class="line"><a id="l00257" name="l00257"></a><span class="lineno">  257</span><span class="comment">   *       items are moot (as opening a session is a prerequisite for anything else).</span></div>
<div class="line"><a id="l00258" name="l00258"></a><span class="lineno">  258</span><span class="comment">   *   - Permissions set on any SHM pool created for a given `&quot;shm::*::Server_session&quot;`. and</span></div>
<div class="line"><a id="l00259" name="l00259"></a><span class="lineno">  259</span><span class="comment">   *     `&quot;shm::*::Session_server&quot;`. A Client_app may not be able to complete its session-open attempt</span></div>
<div class="line"><a id="l00260" name="l00260"></a><span class="lineno">  260</span><span class="comment">   *     (shm::classic::Client_session::sync_connect(), etc.) if its user lacks the permissions to open the</span></div>
<div class="line"><a id="l00261" name="l00261"></a><span class="lineno">  261</span><span class="comment">   *     underlying SHM-pool(s) resource in the file system.(It also conceivably may be able to complete the</span></div>
<div class="line"><a id="l00262" name="l00262"></a><span class="lineno">  262</span><span class="comment">   *     session-open but fail if opening a pool on-demand later; the session will then likely end</span></div>
<div class="line"><a id="l00263" name="l00263"></a><span class="lineno">  263</span><span class="comment">   *     prematurely.  This depends on the inner workings of the particular SHM system chosen;</span></div>
<div class="line"><a id="l00264" name="l00264"></a><span class="lineno">  264</span><span class="comment">   *     shm::classic::Client_session opens pools during session-open procedure exclusively, but other</span></div>
<div class="line"><a id="l00265" name="l00265"></a><span class="lineno">  265</span><span class="comment">   *     systems may behave differently.)</span></div>
<div class="line"><a id="l00266" name="l00266"></a><span class="lineno">  266</span><span class="comment">   *     - Arena-lending SHM providers -- as of this writing namely ipc::shm::arena_lend::jemalloc -- involve</span></div>
<div class="line"><a id="l00267" name="l00267"></a><span class="lineno">  267</span><span class="comment">   *       both sides (session-server and session-client) each creating SHM pool(s) for allocations from</span></div>
<div class="line"><a id="l00268" name="l00268"></a><span class="lineno">  268</span><span class="comment">   *       within their respective processes.  #m_permissions_level_for_client_apps applies to the</span></div>
<div class="line"><a id="l00269" name="l00269"></a><span class="lineno">  269</span><span class="comment">   *       server-created pools, yes; but also client-created pools.  At the moment it seems to me</span></div>
<div class="line"><a id="l00270" name="l00270"></a><span class="lineno">  270</span><span class="comment">   *       (ygoldfel) that nevertheless a common setting in Server_app still makes sense.  In practice, it</span></div>
<div class="line"><a id="l00271" name="l00271"></a><span class="lineno">  271</span><span class="comment">   *       means this: If this is set to util::Permissions_level::S_USER_ACCESS, then the Client_app and</span></div>
<div class="line"><a id="l00272" name="l00272"></a><span class="lineno">  272</span><span class="comment">   *       Server_app UID/GID shall need to be equal; if util::Permissions_level::S_GROUP_ACCESS then just</span></div>
<div class="line"><a id="l00273" name="l00273"></a><span class="lineno">  273</span><span class="comment">   *       the GID (while UIDs ideally would be different).(Obviously if `S_UNRESTRICTED` then does not</span></div>
<div class="line"><a id="l00274" name="l00274"></a><span class="lineno">  274</span><span class="comment">   *       matter.)  Don&#39;t see the sense in making this a separate knob in Client_app.  Maybe though?  Not a</span></div>
<div class="line"><a id="l00275" name="l00275"></a><span class="lineno">  275</span><span class="comment">   *       formal to-do for now.</span></div>
<div class="line"><a id="l00276" name="l00276"></a><span class="lineno">  276</span><span class="comment">   *   - Similarly (to preceding bullet point, minus the `arena_lend` caveat) for bipc MQs.</span></div>
<div class="line"><a id="l00277" name="l00277"></a><span class="lineno">  277</span><span class="comment">   *     ipc::session opens such MQs (if so configured at compile-time) during session-open; hence on permissions</span></div>
<div class="line"><a id="l00278" name="l00278"></a><span class="lineno">  278</span><span class="comment">   *     failure the session-open will itself fail.</span></div>
<div class="line"><a id="l00279" name="l00279"></a><span class="lineno">  279</span><span class="comment">   *   - Similarly (to preceding bullet point) for POSIX MQs.</span></div>
<div class="line"><a id="l00280" name="l00280"></a><span class="lineno">  280</span><span class="comment">   *</span></div>
<div class="line"><a id="l00281" name="l00281"></a><span class="lineno">  281</span><span class="comment">   * As of this writing the list is complete; however it is conceivable it may be analogously extended to more</span></div>
<div class="line"><a id="l00282" name="l00282"></a><span class="lineno">  282</span><span class="comment">   * resources.</span></div>
<div class="line"><a id="l00283" name="l00283"></a><span class="lineno">  283</span><span class="comment">   * @internal</span></div>
<div class="line"><a id="l00284" name="l00284"></a><span class="lineno">  284</span><span class="comment">   * That list is actually not quite complete even as of this writing.  The CNS (PID) file&#39;s shared-mutex</span></div>
<div class="line"><a id="l00285" name="l00285"></a><span class="lineno">  285</span><span class="comment">   * is also subject to this, as are other similar shared-mutexes (in Linux, semaphores).  However that&#39;s very</span></div>
<div class="line"><a id="l00286" name="l00286"></a><span class="lineno">  286</span><span class="comment">   * Inside Baseball to mention in public docs.</span></div>
<div class="line"><a id="l00287" name="l00287"></a><span class="lineno">  287</span><span class="comment">   */</span></div>
<div class="line"><a id="l00288" name="l00288"></a><span class="lineno"><a class="line" href="structipc_1_1session_1_1Server__app.html#abdcd9e8b0287f914496d45a99848be44">  288</a></span>  <a class="code hl_enumeration" href="namespaceipc_1_1util.html#a2ec0bfdddb41a1ef0403e4bb8967705d">util::Permissions_level</a> <a class="code hl_variable" href="structipc_1_1session_1_1Server__app.html#abdcd9e8b0287f914496d45a99848be44">m_permissions_level_for_client_apps</a>;</div>
<div class="line"><a id="l00289" name="l00289"></a><span class="lineno">  289</span>}; <span class="comment">// struct Server_app</span></div>
<div class="line"><a id="l00290" name="l00290"></a><span class="lineno">  290</span> </div>
<div class="line"><a id="l00291" name="l00291"></a><span class="lineno">  291</span><span class="comment">// Free functions: in *_fwd.hpp.</span></div>
<div class="line"><a id="l00292" name="l00292"></a><span class="lineno">  292</span> </div>
<div class="line"><a id="l00293" name="l00293"></a><span class="lineno">  293</span>} <span class="comment">// namespace ipc::session</span></div>
<div class="ttc" id="anamespaceipc_1_1session_html"><div class="ttname"><a href="namespaceipc_1_1session.html">ipc::session</a></div><div class="ttdoc">Flow-IPC module providing the broad lifecycle and shared-resource organization – via the session conc...</div><div class="ttdef"><b>Definition:</b> <a href="app_8cpp_source.html#l00026">app.cpp:27</a></div></div>
<div class="ttc" id="anamespaceipc_1_1util_html_a2ec0bfdddb41a1ef0403e4bb8967705d"><div class="ttname"><a href="namespaceipc_1_1util.html#a2ec0bfdddb41a1ef0403e4bb8967705d">ipc::util::Permissions_level</a></div><div class="ttdeci">Permissions_level</div><div class="ttdoc">Simple specifier of desired access permissions, usually but not necessarily translated into a Permiss...</div><div class="ttdef"><b>Definition:</b> <a href="util__fwd_8hpp_source.html#l00093">util_fwd.hpp:94</a></div></div>
<div class="ttc" id="anamespaceipc_1_1util_html_a3f7d069ce0d23f73153da2e2559dc3d3"><div class="ttname"><a href="namespaceipc_1_1util.html#a3f7d069ce0d23f73153da2e2559dc3d3">ipc::util::group_id_t</a></div><div class="ttdeci">::gid_t group_id_t</div><div class="ttdoc">Syntactic-sugary type for POSIX group ID (integer).</div><div class="ttdef"><b>Definition:</b> <a href="util__fwd_8hpp_source.html#l00149">util_fwd.hpp:149</a></div></div>
<div class="ttc" id="anamespaceipc_1_1util_html_a6435c1b48ec8684c24ca406d1d17208e"><div class="ttname"><a href="namespaceipc_1_1util.html#a6435c1b48ec8684c24ca406d1d17208e">ipc::util::user_id_t</a></div><div class="ttdeci">::uid_t user_id_t</div><div class="ttdoc">Syntactic-sugary type for POSIX user ID (integer).</div><div class="ttdef"><b>Definition:</b> <a href="util__fwd_8hpp_source.html#l00146">util_fwd.hpp:146</a></div></div>
<div class="ttc" id="astructipc_1_1session_1_1App_html"><div class="ttname"><a href="structipc_1_1session_1_1App.html">ipc::session::App</a></div><div class="ttdoc">A description of an application in this ipc::session inter-process communication universe.</div><div class="ttdef"><b>Definition:</b> <a href="app_8hpp_source.html#l00077">app.hpp:78</a></div></div>
<div class="ttc" id="astructipc_1_1session_1_1App_html_a78bb1e984835f429fd44869a83f4b093"><div class="ttname"><a href="structipc_1_1session_1_1App.html#a78bb1e984835f429fd44869a83f4b093">ipc::session::App::m_group_id</a></div><div class="ttdeci">util::group_id_t m_group_id</div><div class="ttdoc">The application must run as this group ID (GID). Files and other shared resources shall have this own...</div><div class="ttdef"><b>Definition:</b> <a href="app_8hpp_source.html#l00171">app.hpp:171</a></div></div>
<div class="ttc" id="astructipc_1_1session_1_1App_html_a8e67b57829fe43a122a23c699b5de8fd"><div class="ttname"><a href="structipc_1_1session_1_1App.html#a8e67b57829fe43a122a23c699b5de8fd">ipc::session::App::m_name</a></div><div class="ttdeci">std::string m_name</div><div class="ttdoc">Brief application name, readable to humans and unique across all other applications' names; used both...</div><div class="ttdef"><b>Definition:</b> <a href="app_8hpp_source.html#l00144">app.hpp:144</a></div></div>
<div class="ttc" id="astructipc_1_1session_1_1App_html_a9e32297579603f2d96616976474d0246"><div class="ttname"><a href="structipc_1_1session_1_1App.html#a9e32297579603f2d96616976474d0246">ipc::session::App::m_user_id</a></div><div class="ttdeci">util::user_id_t m_user_id</div><div class="ttdoc">The application must run as this user ID (UID). Files and other shared resources shall have this owne...</div><div class="ttdef"><b>Definition:</b> <a href="app_8hpp_source.html#l00168">app.hpp:168</a></div></div>
<div class="ttc" id="astructipc_1_1session_1_1App_html_ae82a8635858664720c8546e468f8090b"><div class="ttname"><a href="structipc_1_1session_1_1App.html#ae82a8635858664720c8546e468f8090b">ipc::session::App::m_exec_path</a></div><div class="ttdeci">fs::path m_exec_path</div><div class="ttdoc">Absolute, lexically normalized canonical path to the executable entity (which is not a directory),...</div><div class="ttdef"><b>Definition:</b> <a href="app_8hpp_source.html#l00165">app.hpp:165</a></div></div>
<div class="ttc" id="astructipc_1_1session_1_1App_html_af7527bc1ad0cde62cd4fde97bc1d7ecc"><div class="ttname"><a href="structipc_1_1session_1_1App.html#af7527bc1ad0cde62cd4fde97bc1d7ecc">ipc::session::App::Master_set</a></div><div class="ttdeci">boost::unordered_map&lt; std::string, App &gt; Master_set</div><div class="ttdoc">Suggested type for storing master repository or all Appss. See App doc header for discussion.</div><div class="ttdef"><b>Definition:</b> <a href="app_8hpp_source.html#l00082">app.hpp:82</a></div></div>
<div class="ttc" id="astructipc_1_1session_1_1Client__app_html"><div class="ttname"><a href="structipc_1_1session_1_1Client__app.html">ipc::session::Client_app</a></div><div class="ttdoc">An App that is used as a client in at least one client-server IPC split.</div><div class="ttdef"><b>Definition:</b> <a href="app_8hpp_source.html#l00184">app.hpp:185</a></div></div>
<div class="ttc" id="astructipc_1_1session_1_1Server__app_html"><div class="ttname"><a href="structipc_1_1session_1_1Server__app.html">ipc::session::Server_app</a></div><div class="ttdoc">An App that is used as a server in at least one client-server IPC split.</div><div class="ttdef"><b>Definition:</b> <a href="app_8hpp_source.html#l00205">app.hpp:206</a></div></div>
<div class="ttc" id="astructipc_1_1session_1_1Server__app_html_a12df649b33893270afeac7240a571633"><div class="ttname"><a href="structipc_1_1session_1_1Server__app.html#a12df649b33893270afeac7240a571633">ipc::session::Server_app::m_allowed_client_apps</a></div><div class="ttdeci">Client_app_set m_allowed_client_apps</div><div class="ttdoc">A given Client_app (as identified by its distinct App::m_name) may request to establish an IPC sessio...</div><div class="ttdef"><b>Definition:</b> <a href="app_8hpp_source.html#l00222">app.hpp:222</a></div></div>
<div class="ttc" id="astructipc_1_1session_1_1Server__app_html_a268ca127637100ab10a4ac296aff4fad"><div class="ttname"><a href="structipc_1_1session_1_1Server__app.html#a268ca127637100ab10a4ac296aff4fad">ipc::session::Server_app::Client_app_set</a></div><div class="ttdeci">boost::unordered_set&lt; std::string &gt; Client_app_set</div><div class="ttdoc">Short-hand for existence-checkable set of Client_apps via App::m_name.</div><div class="ttdef"><b>Definition:</b> <a href="app_8hpp_source.html#l00213">app.hpp:213</a></div></div>
<div class="ttc" id="astructipc_1_1session_1_1Server__app_html_a4fa3317f8c57042789940be94f872500"><div class="ttname"><a href="structipc_1_1session_1_1Server__app.html#a4fa3317f8c57042789940be94f872500">ipc::session::Server_app::m_kernel_persistent_run_dir_override</a></div><div class="ttdeci">fs::path m_kernel_persistent_run_dir_override</div><div class="ttdoc">Absolute path to the directory (without trailing separator) in the file system where kernel-persisten...</div><div class="ttdef"><b>Definition:</b> <a href="app_8hpp_source.html#l00242">app.hpp:242</a></div></div>
<div class="ttc" id="astructipc_1_1session_1_1Server__app_html_abdcd9e8b0287f914496d45a99848be44"><div class="ttname"><a href="structipc_1_1session_1_1Server__app.html#abdcd9e8b0287f914496d45a99848be44">ipc::session::Server_app::m_permissions_level_for_client_apps</a></div><div class="ttdeci">util::Permissions_level m_permissions_level_for_client_apps</div><div class="ttdoc">Specifies level of access for Client_apps (which must, also, be in m_allowed_client_apps at any rate)...</div><div class="ttdef"><b>Definition:</b> <a href="app_8hpp_source.html#l00288">app.hpp:288</a></div></div>
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